We're hiring a TikTok Content Creator (paid opportunity). Click here to learn more.
Question 1
The Earth--atmosphere system is in approximate dynamic equilibrium over a long time interval. What condition must be satisfied by the mean radiation intensities crossing the boundary of this system?
A.
Mean reflected intensity equals mean emitted infrared intensity.
B.
Mean outgoing infrared intensity is always less than incoming intensity.
C.
Mean incoming solar intensity equals mean outgoing intensity.
D.
Mean incoming solar intensity is zero at night.
Question 2
A surface scatters of the solar radiation incident on it. What is the albedo of the surface?
A.
B.
C.
D.
Question 3
The row that lists only main greenhouse gases is
A.
, , ,
B.
, , ,
C.
, , ,
D.
, , ,
Question 4
A large area of sea ice melts and is replaced by open ocean. What is the expected direct effect on the local absorption of solar radiation?
A.
Absorption increases because the albedo decreases.
B.
Absorption increases because the emissivity decreases.
C.
Absorption decreases because the solar constant decreases.
D.
Absorption decreases because the albedo decreases.
Question 5
The solar constant at a planet is . The planet has albedo . What is the mean absorbed solar intensity over the whole surface of the planet?
A.
B.
C.
D.
Question 6
A greenhouse-gas molecule absorbs an infrared photon emitted by Earth's surface. What best describes the subsequent emission of infrared radiation by the molecule?
A.
It is stored permanently in molecular energy levels.
B.
It is emitted in all directions, so some may travel back toward the surface.
C.
It is converted completely into visible light travelling downward.
D.
It is emitted only upward, so all of it escapes directly to space.
Question 7
A grey surface at temperature radiates . A black surface at the same temperature radiates . What is the emissivity of the grey surface?
A.
B.
C.
D.
Question 8
A planet orbits a star at twice Earth's distance from the Sun. The star has the same luminosity as the Sun. The solar constant at Earth is . What is the stellar radiation intensity at the planet?
A.
B.
C.
D.
Question 9
The Earth-atmosphere system is modelled over a long time interval. Solar radiation enters the system and radiation also leaves the system.
State the condition for the Earth-atmosphere system to be in radiative dynamic equilibrium.
[1]
Explain what happens to the average temperature of the system if the mean incoming radiation intensity is greater than the mean outgoing radiation intensity.
[2]
0
Question 10
Greenhouse gases form only a small fraction of Earth's atmosphere, but they are important in the energy balance.
State two main greenhouse gases other than carbon dioxide.
[1]
Outline one natural origin and one human-created or human-enhanced origin of methane.
[2]
State why nitrogen and oxygen are not considered main greenhouse gases.
[1]
0
Question 11
A spherical airless moon has emissivity and albedo . It is in radiative equilibrium at distance where the solar constant is . The equilibrium temperature is proportional to
A.
B.
C.
D.
Question 12
In a simple greenhouse model, the surface temperature satisfies
The albedo and solar constant remain unchanged. What happens to when the fraction of surface-emitted infrared radiation returned to the surface increases?
A.
increases because the solar constant must increase.
B.
increases because a smaller fraction of surface radiation escapes directly.
C.
decreases because the atmosphere emits less radiation downward.
D.
remains constant because the absorbed solar intensity is unchanged.
Question 13
The resonance model explains infrared absorption by greenhouse gases using molecular vibrations. What additional condition is needed for a vibrational mode to absorb infrared radiation strongly?
A.
The vibration must reflect visible light efficiently.
B.
The molecule must have a temperature lower than the surface.
C.
The vibration must involve a changing electric dipole.
D.
The molecule must be the most abundant gas in the atmosphere.
Question 14
A grey surface of area is at a temperature of . The total power radiated by the surface is .
Calculate the emissivity of the surface.
[3]
0
Question 15
During spring, a polar surface receives a total incident solar power of . The total scattered power from the surface is .
Calculate the albedo of the polar surface.
[2]
Explain why melting of ice or snow can produce a positive feedback on warming.
[2]
0
Question 16
The luminosity of the Sun is . The mean Earth-Sun distance is .
Calculate the solar constant at the mean Earth-Sun distance.
[2]
Outline why the small yearly change in Earth-Sun distance is not the main cause of the seasons.
[2]
0
Question 17
A planet of radius receives radiation from its star with solar constant .
Explain why the mean incoming intensity over the whole surface of the planet is before reflection is considered.
[2]
For Earth, take and albedo . Calculate the mean absorbed solar intensity.
[2]
0
Question 18
Two surfaces are heated to different temperatures. The graph shows the radiated power per unit area plotted against for each surface.
Determine the emissivity of surface A.
[2]
Compare the radiation emitted per unit area by surfaces A and B at the same temperature.
[1]
Suggest why visible colour alone is not sufficient to decide which surface is the better infrared emitter.
[1]
0
Question 19
Satellite measurements of reflected solar radiation were made for different latitude bands and cloud conditions.
| Latitude band | Cloud condition | Incident power / 10^14 W | Reflected power / 10^14 W |
|---|---|---|---|
| Near equator | Clear sky | 3.0 | 0.30 |
| Near equator | Cloudy | 3.0 | 0.60 |
| Mid-latitude | Clear sky | 3.0 | 0.75 |
| Mid-latitude | Cloudy | 3.0 | 1.20 |
| High latitude | Clear sky | 3.0 | 1.20 |
| High latitude | Cloudy | 3.0 | 1.80 |
Calculate the albedo for the cloudy high-latitude region.
[1]
Describe two trends shown by the data.
[2]
Suggest the effect on the local energy balance if high-latitude sea ice is replaced by open ocean.
[1]
0
Question 20
The table gives approximate atmospheric concentrations of selected greenhouse gases before industrialization and at present, together with examples of human-related sources.
| Greenhouse gas | Before industrialization / ppm | Present / ppm | Example human-related source(s) |
|---|---|---|---|
| Carbon dioxide | 280 | 415 | Fossil-fuel combustion; deforestation |
| Methane | 0.72 | 1.92 | Livestock; rice paddies; landfill |
| Nitrous oxide | 0.27 | 0.33 | Fertilizer use; manure management; combustion |
Calculate the percentage increase in the concentration of methane shown in the table.
[2]
State one human-related origin of the increase in nitrous oxide concentration.
[1]
Outline why water vapour is often described as a feedback rather than the primary human driver of the enhanced greenhouse effect.
[1]
0
Question 21
A satellite surface of area and emissivity is at . Its surroundings are at . Using , which expression gives the net radiative power loss of the surface?
A.
B.
C.
D.
Question 22
An airless moon orbits a star where the solar constant at the moon is . The moon has albedo and infrared emissivity . Assume the moon reaches radiative equilibrium and has a uniform surface temperature.
Calculate the equilibrium temperature of the moon.
[4]
0
Question 23
A simple model of the greenhouse effect is
where is the fraction of surface-emitted infrared radiation returned to the surface by the atmosphere. For Earth take , and .
Calculate the value of in this model.
[3]
State the effect on the equilibrium surface temperature if greenhouse-gas concentration increases , with all other quantities unchanged.
[1]
0
Question 24
The graph shows the transmittance of Earth's atmosphere for infrared radiation emitted by the surface. Several absorption bands are labelled with the main absorbing gases.
| Wavelength / µm | Transmittance / % | Band label |
|---|---|---|
| 2.7 | 15 | H2O |
| 4.3 | 5 | CO2 |
| 6.3 | 10 | H2O |
| 8.0 | 75 | atmospheric window |
| 9.6 | 15 | O3 |
| 10.5 | 85 | atmospheric window |
| 15.0 | 1 | CO2 |
| 18.0 | 30 | H2O |
State what a low value of transmittance at a particular wavelength means for infrared radiation at that wavelength.
[1]
Explain how absorption bands due to greenhouse gases reduce the rate at which the surface cools to space.
[2]
0
Question 25
A region of sea ice receives a mean incident solar intensity of during summer. Its albedo changes from when ice covered to after melting exposes ocean water.
Calculate the increase in mean absorbed solar intensity caused by the change in albedo.
[2]
Explain why cloud cover makes Earth's albedo variable and why this makes the net climate effect of clouds difficult to predict from albedo alone.
[2]
0
Question 26
In a simplified energy-balance model, increased greenhouse-gas concentration increases the fraction of surface infrared radiation absorbed and returned by the atmosphere.
State the name given to the human-caused augmentation of the greenhouse effect.
[1]
Explain, using conservation of energy, why the average surface temperature rises when more infrared radiation is returned to the surface.
[2]
Suggest one limitation of representing the atmosphere by a single returned fraction of infrared radiation.
[1]
0
Question 27
A simplified model is used to estimate the equilibrium temperature of a rocky planet with no greenhouse atmosphere. The table gives values for a planet labelled X.
| Planet | Solar constant / W m^-2 | Albedo | Emissivity |
|---|---|---|---|
| X | 900 | 0.22 | 0.85 |
| Y | 1200 | 0.30 | 0.90 |
| Z | 700 | 0.15 | 0.75 |
| W | 500 | 0.35 | 0.95 |
State why the mean incoming solar intensity over the whole surface of the planet is less than the solar constant at the planet.
[1]
Determine the mean absorbed solar intensity for planet X.
[2]
Calculate the equilibrium temperature of planet X.
[2]
0
Question 28
A spacecraft measures the solar intensity at different distances from the Sun. The graph shows intensity plotted against , where is the distance from the Sun.
State the relationship between solar intensity and distance from the Sun shown by the graph.
[1]
Use the graph to determine the luminosity of the Sun.
[2]
Explain why the annual variation in solar intensity due to Earth's elliptical orbit is not the main cause of the seasons.
[1]
0
Question 29
The graph shows atmospheric transmittance at different wavelengths together with the approximate wavelength range of infrared radiation emitted by Earth's surface.
Identify one wavelength region in which radiation emitted by Earth's surface is strongly absorbed by the atmosphere.
[1]
Explain, in terms of molecular energy levels, why greenhouse gases absorb infrared radiation at particular wavelengths.
[2]
Explain how absorption and re-emission by the gases shown can increase Earth's mean surface temperature.
[2]
0
Question 30
A climate model region in the Arctic is monitored over several decades. The graph shows changes in summer sea-ice fraction, regional albedo and mean absorbed solar intensity.
| Year | Summer sea-ice fraction / fraction | Regional albedo / fraction | Mean absorbed solar intensity / W m^-2 |
|---|---|---|---|
| 1980 | 0.84 | 0.62 | 68.4 |
| 1990 | 0.74 | 0.59 | 73.8 |
| 2000 | 0.66 | 0.55 | 81.0 |
| 2010 | 0.55 | 0.51 | 88.2 |
| 2020 | 0.43 | 0.48 | 93.6 |
Using a mean incident solar intensity of , calculate the increase in absorbed solar intensity when the albedo changes from to .
[2]
Describe the relationship between sea-ice fraction and albedo shown by the data.
[1]
Suggest why the change shown is a positive feedback in the climate system.
[2]
0
Question 31
A simplified model links the use of different electricity-generation methods to changes in atmospheric greenhouse-gas concentration. The graph shows the modelled change in surface temperature as a function of the change in returned-infrared fraction . A table gives direct operational carbon dioxide emissions for several electricity-generation methods.
| Dataset | Delta k | Delta T / K | Method | CO2 / g kWh^-1 |
|---|---|---|---|---|
| Temperature | -0.050 | -6.0 | — | — |
| Temperature | -0.025 | -3.0 | — | — |
| Temperature | 0.000 | 0.0 | — | — |
| Temperature | 0.025 | 3.0 | — | — |
| Temperature | 0.050 | 6.0 | — | — |
| Emissions | — | — | Coal | 820 |
| Emissions | — | — | Gas | 490 |
| Emissions | — | — | Oil | 650 |
| Emissions | — | — | Wind | 0 |
| Emissions | — | — | Nuclear | 0 |
| Emissions | — | — | Hydroelectric | 0 |
| Emissions | — | — | Solar | 0 |
Determine the gradient of the graph near .
[2]
Identify one electricity-generation method in the table with very low direct operational emissions.
[1]
Explain the physics link between burning fossil fuels for electricity and an increase in the returned-infrared fraction .
[1]
0
Question 32
The diagram shows two simplified vibrational modes of a carbon dioxide molecule.
Explain, using a resonance model, why some infrared frequencies are absorbed strongly by greenhouse-gas molecules.
[2]
Suggest why the symmetric stretch of absorbs infrared radiation weakly, while a bending vibration absorbs infrared radiation strongly.
[2]
0
Question 33
A one-parameter model represents the atmosphere by the fraction of surface-emitted infrared radiation returned to the surface:
The graph shows equilibrium surface temperature as a function of for a planet with Earth-like values of and .
Determine the value of corresponding to a surface temperature of , using and .
[2]
Calculate the new equilibrium surface temperature if increases to while and remain unchanged.
[2]
Explain why a higher value of requires a higher equilibrium surface temperature in this model.
[1]
0
Question 34
The diagram shows a simplified annual mean energy budget for the Earth-atmosphere system. Some energy transfers are between the surface and atmosphere, while others cross the boundary of the Earth-atmosphere system.
Determine the infrared intensity escaping directly from the surface to space through the atmospheric window.
[1]
Calculate the non-radiative transfer of energy from the surface to the atmosphere.
[2]
Explain why the diagram can represent dynamic equilibrium even though large energy transfers occur within the system.
[2]
0
Question 35
The figure compares part of Earth's infrared emission spectrum with absorption features for a greenhouse gas. A simplified molecular energy-level diagram is also shown.
| Wavelength / μm | Earth emission / a.u. | Gas absorption / a.u. | Molecular transition |
|---|---|---|---|
| 8.0 | 0.20 | 0.05 | — |
| 10.0 | 1.00 | 0.10 | — |
| 12.0 | 0.82 | 0.18 | — |
| 14.0 | 0.60 | 0.65 | — |
| 15.0 | 0.45 | 1.00 | allowed vibrational transition |
| 16.0 | 0.35 | 0.80 | — |
| 18.0 | 0.15 | 0.12 | — |
Calculate the photon energy for radiation of wavelength .
[2]
Explain why this wavelength can be strongly absorbed by the molecule shown.
[1]
State one limitation of using only a classical resonance model to explain the absorption spectrum.
[1]
0
Question 36
A small icy moon orbits a star. The solar constant at the moon is . The mean albedo of the moon is and its infrared emissivity is .
The energy balance for the moon is to be estimated using a uniform-temperature model.
I.
State what is meant by the albedo of the moon.
[1]
II.
Explain why the mean incident solar intensity before reflection is .
[2]
Calculate the equilibrium temperature of the moon, assuming that there is no greenhouse atmosphere.
[2]
Discuss how partial melting of surface ice could change the later temperature of the moon.
[2]
0
Question 37
Two roof materials are tested at the same temperature of . Each roof receives the same incident solar intensity. The table gives measured radiation data.
| Material | Incident solar intensity / W m^-2 | Reflected solar intensity / W m^-2 | Emitted infrared intensity / W m^-2 |
|---|---|---|---|
| X | 1000 | 300 | 413 |
| Y | 1000 | 150 | 368 |
Use the data in the table to compare the two roof materials.
I.
Determine the albedo of material X from its reflected and incident solar intensities.
[1]
II.
Determine the infrared emissivity of material X.
[2]
Explain why albedo and emissivity are not the same physical property.
[2]
Evaluate which roof material is more suitable for reducing daytime warming of a building.
[1]
0
Question 38
Satellite measurements indicate that the Earth-atmosphere system has a mean positive energy imbalance of over the whole surface of Earth. The radius of Earth is .
Consider the meaning of energy balance for the Earth-atmosphere system.
I.
State the condition for dynamic equilibrium of the Earth-atmosphere system.
[1]
II.
Explain why a positive imbalance causes warming even though the imbalance is small compared with the solar constant.
[2]
Calculate the total rate at which energy is being gained by the Earth-atmosphere system.
[2]
Explain how increased greenhouse-gas concentration can produce such an imbalance.
[3]
0
Question 39
A survey compares three airless moons orbiting different stars. The table gives the stellar constant at each moon, its mean albedo, its infrared emissivity and its measured mean surface temperature.
| Moon | Stellar constant / W m^-2 | Mean albedo | Infrared emissivity | Measured mean surface temperature / K |
|---|---|---|---|---|
| A | 800 | 0.35 | 0.90 | 233 |
| B | 600 | 0.10 | 0.60 | 245 |
| C | 400 | 0.50 | 0.95 | 179 |
Calculate the equilibrium temperature predicted for moon B using the data in the table.
[2]
Compare the effects of high albedo and low emissivity on the equilibrium temperature of a moon.
[2]
Suggest one reason why the measured mean surface temperature of a real moon could differ from the value predicted by this simple radiative model.
[1]
0
Question 40
The main gases in dry air are nitrogen and oxygen, but the main greenhouse gases include , , and .
Consider the origin of greenhouse gases.
I.
Identify two greenhouse gases other than water vapour.
[1]
II.
For one gas identified in (a)(i), outline one natural origin and one human-enhanced origin.
[2]
Explain the absorption and re-emission of infrared radiation by greenhouse-gas molecules in terms of molecular energy levels.
[3]
Suggest why nitrogen and oxygen are not listed as main greenhouse gases.
[1]
0
Question 41
A planet orbits a star of luminosity at a mean orbital radius of . The planet has albedo and infrared emissivity .
Use the inverse-square model for radiation from the star.
I.
Explain why the intensity at the planet is given by .
[2]
II.
Calculate the solar constant at the planet.
[1]
Determine the equilibrium temperature of the planet if it has no greenhouse atmosphere.
[2]
Discuss one limitation of this estimate for the real surface temperature of the planet.
[2]
0
Question 42
In a simple greenhouse model for Earth,
where is the fraction of surface-emitted infrared radiation returned to the surface. Take , and .
Use the model to quantify the greenhouse effect.
I.
Determine the value of for the given data.
[2]
II.
Calculate the new surface temperature if increases by while and remain unchanged.
[2]
Explain why the burning of fossil fuels is a primary cause of the enhanced greenhouse effect.
[2]
Evaluate whether this simple model proves that the calculated temperature rise will occur exactly in the real climate system.
[2]
0
Question 43
A simplified model of a planet's atmosphere uses
where is the fraction of surface infrared radiation returned to the surface. For the planet, and . The present value of is estimated to be .
The present value of is estimated to be .
I.
Determine the present surface temperature predicted by the model.
[2]
II.
An enhanced greenhouse effect increases to . Calculate the change in surface temperature.
[2]
Explain, using conservation of energy, why the surface temperature must rise when increases and and do not change.
[2]
Discuss two assumptions in this model that limit its use for predicting a real climate.
[2]
0
Question 44
A satellite records the transmittance of Earth's atmosphere at different infrared wavelengths. Strong absorption bands are observed near wavelengths associated with vibrations of , and .
Interpret the transmittance spectrum.
I.
State what is meant by a low transmittance at a particular infrared wavelength.
[1]
II.
Explain why absorption occurs only in particular wavelength bands.
[2]
Compare the resonance model and the molecular energy-level model for greenhouse-gas absorption.
[3]
Evaluate one limitation of using only a simple resonance model to explain the greenhouse effect.
[2]
0
Question 45
Because Earth's orbit is elliptical, the solar constant is about at one time of year and about six months later. Assume for this question that albedo and emissivity remain constant.
Consider the effect of the changing solar constant on a simple equilibrium-temperature model.
I.
Show that, if albedo and emissivity are unchanged, the equilibrium temperature is proportional to .
[2]
II.
Estimate the temperature difference between the two orbital positions if the lower-solar-constant equilibrium temperature is .
[1]
Explain why this variation in solar constant is not the main cause of seasons on Earth.
[2]
Discuss why the same change in solar constant does not produce an immediate uniform change in surface temperature everywhere on Earth.
[2]
0
Question 46
Two cloud layers are considered in a climate model. Cloud layer A is thick and bright. Cloud layer B is thin and high. Both affect incoming solar radiation and outgoing infrared radiation.
| Cloud layer | Description | Incoming SW / W m^-2 | SW reflected / W m^-2 | SW reaching surface / W m^-2 | LW absorbed / W m^-2 | LW returned downward / W m^-2 |
|---|---|---|---|---|---|---|
| A | thick, bright, low | 300 | 240 | 60 | 35 | 20 |
| B | thin, high | 300 | 60 | 240 | 120 | 80 |
Analyse the competing effects of clouds on Earth's radiation balance.
I.
Explain how a thick bright cloud can reduce surface warming during the day.
[2]
II.
Explain how a thin high cloud can increase surface warming at night.
[2]
Evaluate why the statement 'more cloud always cools Earth' is not a valid conclusion from physics.
[3]
Suggest one reason why daily variation in cloud cover causes daily variation in Earth's albedo.
[1]
0
Question 47
An exoplanet receives a stellar constant of and has albedo . Its measured mean surface temperature is . Assume the surface behaves as a black body and use the simple model
Use the measured temperature to infer the effect of the atmosphere.
I.
Calculate the mean absorbed stellar intensity.
[1]
II.
Determine the value of required by the model.
[3]
Calculate the equilibrium temperature the exoplanet would have in the absence of a greenhouse atmosphere, keeping the same albedo.
[2]
Discuss whether a large value of alone identifies which greenhouse gas is present.
[2]
0
Question 48
In one Arctic summer, an area of sea ice is replaced by open ocean. During the affected period the mean incident solar intensity on this region is for days. The albedo of sea ice is and the albedo of open ocean is .
Estimate the additional solar energy absorbed because of the change in surface.
I.
Calculate the increase in absorbed intensity for the changed region.
[2]
II.
Calculate the additional energy absorbed during the days.
[2]
Explain why this albedo change is described as a positive feedback in climate physics.
[2]
Evaluate one limitation of using the calculation in (a) to predict the actual temperature change of the Arctic Ocean.
[2]
0
The Fast Track To Your
Best IB Coursework & College Essays
All content on this website has been developed independently from and is not endorsed by the International Baccalaureate Organization. International Baccalaureate and IB are registered trademarks owned by the International Baccalaureate Organization.